Hello, I'm working with a communications gateway that has Modbus capability. I used the Modbus libraries to communicate with this device; however, I have a problem with some of the starting addresses. For my communications gateway, several starting addresses are Unit32, and the Modbus library is designed for starting addresses of Unit16. I tried manually changing the input from U16 to U32, but there was no response. The communications gateway does respond when the starting address is at U16, but the output register is not accurate. Thanks in advance, Jose

LabVIEW

Modbus Unit32 starting address

Author

Kevin,

No, I'm not getting consistent amounts of bytes. They vary from 0 to over a hundred.

Jose

Message 11 of 12

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Hey Jose,

If you know how many bytes of data you are expecting to receive I would set up your code to wait (at least up to a certain timeout) until there are that many bytes at the port. It seems like you may just not be waiting long enough after the write to perform your read.

Kevin Fort
Principal Software Engineer
NI